AE LOCK?

Can someone please explain AE Lock to me? If you press the AE lock button it "locks" your exposure......isn't it already locked if you are shooting in manual?

I'm trying to make sense of my * and AE LOCK, and shutter button functions.

AE lock doesn't matter if you shoot manual. It's there to be able to meter then recompose when in AV or TV. Same when shooting flash in ETTL mode (FEL). Both use the the center AF spot (except in 1D bodies).

On the note of using it with flash, the other day I was on M with flash which of course still meters the flash (flash not set to manual). I tried to use AE lock thinking I might lock the flash exposure with the pre-flash, but it didn't seem to work.

It does actually still work in Manual. Bear with me on the explanation though. I use M in most of my shots, but I also use Auto ISO. I still pick my shutter and aperture based on the type of shot I would like to take though. But I do still need to user AE lock of I want to make sure I am getting a shot that I want.
An example, I am looking at the most amazing sunset in the history of time. I bring the camera up, I compose with my horizon in the top third so I don't get too much of the sky. I take the shot, and I get... a fantastic shot with the ground perfectly exposed and the sky blown own. So I then meter on the sky, hit the AE button to lock that exposure and then recompose and focus on the ground and then my brilliant sunset if perfectly exposed.
Or vice versa.
If I was not using Auto ISO, then you are 100% correct, you are metering on the location you half press the shutter, even if you recompose afterwards.

sirquack - Yes, AE lock works like that, but I would say that many would say that M mode and Auto ISO isn't really manual.

AE lock works in any semi-automatic mode. For many of us, semi-automatic means letting the camera have control of one of the points of the exposure triangle. You are still doing that, so you are using some kind of semi-automatic mode that doesn't really have a name because it wasn't possible with film. Note, that I am not a "manual snob" - I am almost always in Av. I just think it is interesting that some think of "manual" as controling all three aspects, and some think of manual as M-Mode on the dial. We just don't really have a term for M+Auto ISO vs M+Selected ISO.

AE lock is useful if you want to lock in an exposure and then focus and recompose.

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5d iii has AE lock and HOLD.

How do you use AE lock with back button focus then?

Separate buttons. Ae lock first then bbf with the rear focus button

Blurr Cube wrote in post #17356727
5d iii has AE lock and HOLD.

This is Good info, I didn't even know I could do this (should really read my manual one day)

Hmmm.... Okay. I pointed my camera at a wall, pressed AE lock, the viewfinder showed it was on, then when I push BBF the indicator for AE lock goes away.

jeljohns wrote in post #17362534
Hmmm.... Okay. I pointed my camera at a wall, pressed AE lock, the viewfinder showed it was on, then when I push BBF the indicator for AE lock goes away.

You need to assign BBF AND disable AF from the shutter button. Here's a vid.

Ahhh ok, so the regular AE Lock is just for one picture (manual says it stays on 4 seconds.) but AE LOCK + HOLD is the one needed for multiple shots. Is my understanding correct? There is nothing in the manual about AE LOCK + Hold.

I'm still having trouble wrapping my head around all the AE lock stuff though...

jeljohns wrote in post #17362722
Ahhh ok, so the regular AE Lock is just for one picture (manual says it stays on 4 seconds.) but AE LOCK + HOLD is the one needed for multiple shots. Is my understanding correct? There is nothing in the manual about AE LOCK + Hold.

I'm still having trouble wrapping my head around all the AE lock stuff though...

Pretty much. I think there's a brief mention of AE Lock Hold or *H in the Custom Controls section.

Jeljohns,

I don't know which camera you have but here's what my Canon 6D manual says (p. 325)

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